Abstract
The study presented here examines the criticality behavior of a thorium-based molten salt reactor (TMSR) with various design parameters. In the current study, TMSR has been designed to have two zones in the core. The same fuel salt is moving in both zones, while the size of the fuel channel diameters differs for each zone. The outer zone is planned to act as a blanket. First, two fuel lattice configurations, which have hexagonal and hexahedral geometries, were analyzed. As a first observation, hexagonal geometry allows us to place more fuel channels than hexahedral ones for the same active core diameter. Then, two moderator materials, graphite and BeO, are compared for the maximum thermal neutron efficiency. Although BeO is a better moderator and gives a higher effective multiplication factor (keff), the reactor reaches criticality with a smaller fuel channel diameter with a graphite moderator when it is under-moderated In addition, different molten salts are studied as both coolant and fuel salt materials to examine other isotopes' effects on criticality and determine the most fuel-efficient salt This part of the study aims to reach criticality with a lower fuel inventory. Finally, we looked for the neutron flux distribution of the reactor. This reactor is intended to produce 2000 MWth of power, so the uniform thermal neutron flux for that power is calculated as 5.55E+16 n/cm2s with graphite moderator and FLiBe fuel salt.
